Aspinall Unit operations update: Blue Mesa releases to be bumped up to meet reservoir icing targets

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be increased to 1600 cfs on Monday, December 9th. Blue Mesa Reservoir elevation remains above the winter icing target level. Releases will be maintained at this level with the goal of lowering the reservoir to the icing target elevation of 7490 feet by December 31st. Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for September through December.

Currently, there are no diversions into the Gunnison Tunnel and flows in the Gunnison River through the Black Canyon are around 1000 cfs. After this release change Gunnison Tunnel diversions will still be at zero and flows in the Gunnison River through the Black Canyon will be around 1600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

Aspinall Unit

Aspinall Unit operations update: Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs

Gunnison River Basin. By Shannon1 – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=69257550

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be increased by 200 cfs, today, September 30th. Releases will be decreased by 200 cfs late Friday, October 4th. Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for September through December.

Currently, diversions into the Gunnison Tunnel are 1040 cfs and flows in the Gunnison River through the Black Canyon will increase to 800 cfs today. At the end of this week Gunnison Tunnel diversions will still be 1040 cfs and flows in the Gunnison River through the Black Canyon will return to 600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

Aspinall unit operations update: Flows in the Gunnison Tunnel ~= 1030 CFS

Grand opening of the Gunnison Tunnel in Colorado 1909. Photo credit USBR.

From email from Reclamation (Erik Knight):

Releases from the Aspinall Unit will be increased by 100 cfs, today, September 9th. Reservoir contents at Morrow Pt and Crystal have sufficiently recovered to allow for higher releases. Flows in the lower Gunnison River are currently above the baseflow target of 1050 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for September through December.

Currently, diversions into the Gunnison Tunnel are 1030 cfs and flows in the Gunnison River through the Black Canyon are around 500 cfs. After this release change Gunnison Tunnel diversions will still be 1030 cfs and flows in the Gunnison River through the Black Canyon will be around 600 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

Aspinall Unit Operations update: Streamflow in the Black Canyon ~515 cfs

From email from the Bureau of Reclamation (Ryan Christianson):

Releases from the Aspinall Unit will be decreased by 100 cfs at approximately 10am on Tuesday, September 3rd. Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1050 cfs for September. This release decrease will allow for the recovery of storage in Crystal Reservoir that was utilized in response to upstream facility outages.

Currently, diversions into the Gunnison Tunnel are approximately 1200 cfs and flows in the Gunnison River through the Black Canyon are around 615 cfs. After this release change, the Gunnison Tunnel diversions will remain near 1200 cfs and flows in the Gunnison River through the Black Canyon will be around 515 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.

Looking downstream from Chasm View, Painted Wall on right. Photo credit: NPS\Lisa Lynch

The August “#GunnisonRiver Basin News” is hot off the presses

Click here to read the newsletter from the Gunnison Basin Roundtable. Here’s an excerpt:

August in the Basin: High and Dry!

Bountiful snowmelt and increased soil moisture conditions, resulted in “boomer” inflows, boosting basin reservoirs levels and causing an amazing recovery from last year’s low levels – this included Blue Mesa, Colorado’s largest reservoir – with over 160 percent of average inflow volume. Although most of the snow has melted, the Upper Basin rivers are still flowing at higher than average rates, even in the face of drying conditions (July and August precipitation has been generally below average).

Also, very importantly Lake Powell – the Upper Basin’s largest water storage and management facility received an inflow volume of 145% of average.

Current conditions and Aspinall Unit operations

Aspinall Unit dams

@USBR: The next Aspinall Operations meeting will be held on Thursday, August 15th, at the Elk Creek Visitor Center at Blue Mesa Reservoir. Start time is 1:00 PM

Aspinall Unit operations update: Gunnison Tunnel diversions = 950 cfs, Gunnison River through the Black Canyon = 2550 cfs

Gunnison Tunnel via the National Park Service

From email from Reclamation (Ryan Christianson):

Releases from the Aspinall Unit were increased by 500 cfs beginning on Friday, July 26th and are scheduled to continue at that rate into the near future in order to prevent Blue Mesa Reservoir from overfilling. At the current inflow and release rate it is projected that Blue Mesa Reservoir would begin spilling, as the reservoir is now full. The current forecast for the April-July runoff volume for Blue Mesa Reservoir is 1,075,000 AF of inflow, which is 159% of average. Flows in the lower Gunnison River are currently above the baseflow target of 1500 cfs. River flows are expected to stay above the baseflow target for the foreseeable future.

Pursuant to the Aspinall Unit Operations Record of Decision (ROD), the baseflow target in the lower Gunnison River, as measured at the Whitewater gage, is 1500 cfs for July and August.

Currently, diversions into the Gunnison Tunnel are 950 cfs and flows in the Gunnison River through the Black Canyon are around 2550 cfs. Current flow information is obtained from provisional data that may undergo revision subsequent to review.